KR101119448B1 - Method of purifying protein - Google Patents

Abstract

Challenge: To provide a method for purifying bioactive proteins, particularly antibodies, that can reliably remove impurities such as DNA contaminants and viruses in a simpler way that reduces the cost and loss of bioactive proteins.

Solution: A method for removing impurities in a biologically active protein-containing sample, comprising the following steps:

1) making a sample containing a bioactive protein into an aqueous solution of low conductivity at a pH lower than the isoelectric point of the bioactive protein: and

2) removing the resulting particles.

Description

Protein purification method {METHOD OF PURIFYING PROTEIN}

The present invention relates to a method for purifying proteins, and more particularly, to a method for removing impurities such as DNA contaminants from a sample containing a bioactive protein such as an antibody.

With the development of genetic recombination technology, various protein preparations have been provided in a stable supply. In particular, recently, various recombinant antibody drugs with high selectivity compared to conventional medicines have been developed and are currently in clinical trials.

In preparations containing bioactive proteins produced by such recombination, it is necessary to remove impurities such as DNA contaminants caused by contamination of host DNA and viruses. According to current World Health Organization (WHO) standards, the amount of DNA in a biopharmaceutical should not exceed 100 pg DNA per dose. In order to satisfy this criterion, DNA is generally removed by treating an aqueous medium containing a physiologically active protein obtained from a host cell by anion exchange chromatography, hydroxy apatite chromatography, or a combination thereof.

In particular, when the physiologically active protein is an antibody obtained by recombination in a mammalian host cell, protein A or Protein G binds to the Fc chain of IgG, and the aqueous medium is subjected to affinity column chromatography of Protein A or Protein G. It is then purified by various chromatography.

For example, Japanese Patent Application Laid-open No. Hei 5-504579 applies an antibody-containing aqueous medium obtained from mammalian cell culture to Protein A / G column chromatography to absorb antibody molecules into a column, followed by acidic solution (concentration of about 0.1). The antibody molecule is eluted using M citric acid, pH 3.0-3.5). The resulting acidic eluate is subjected to ion exchange column chromatography and size exclusion column chromatography sequentially to obtain purified antibody molecules.

However, these various chromatographic processes and combinations thereof are time-consuming, labor-intensive, costly, cumbersome, and ineffective.

It is an object of the present invention to provide a method of purifying bioactive proteins, in particular antibodies, which can reliably remove impurities such as DNA contaminants and viruses, and can minimize the loss of bioactive proteins in a simpler and cheaper way.

DISCLOSURE OF INVENTION

As a result of intensive studies to solve the above problems, the inventors surprisingly formed a sample containing a bioactive protein in an aqueous solution of low conductivity at a pH lower than the isoelectric point of the bioactive protein, and filtering with a filter. The present invention was completed by finding out that by removing the generated particles, impurities such as DNA contaminants and viruses can be efficiently removed from the sample without a complicated chromatography process.

That is, the present invention provides the following.

(1) a method for removing impurities from a biologically active protein-containing sample, comprising the following steps:

1) forming a sample containing a bioactive protein in an aqueous solution of low conductivity at a pH below the isoelectric point of the bioactive protein; And

2) removing the generated particles.

(2) The method according to (1), wherein the conductivity of the low conductivity aqueous solution is 0 to 100 mM of molar concentration.

(3) The method according to (1) or (2), wherein the ionic strength of the low conductivity aqueous solution is 0 to 0.2.

(4) The method according to any one of (1) to (3), wherein the conductivity of the low conductivity aqueous solution is 0 to 300 mS / m.

(5) The method according to any one of (1) to (4), wherein the solution is selected from aqueous solutions of hydrochloric acid, citric acid and acetic acid.

(6) The method according to any one of (1) to (5), wherein the pH of the aqueous solution is equal to or less than the isoelectric point of the bioactive protein and equal to or more than pH 2.0.

(7) The method according to any one of (1) to (6), wherein the impurity is a DNA contaminant.

(8) The method according to any one of (1) to (6), wherein the impurity is a virus.

(9) The method according to (7), wherein the DNA contaminants in the biologically active protein-containing sample after the DNA contaminant removal treatment are 22.5 pg / ml or less in DNA concentration.

(10) The method according to any one of (1) to (9), wherein the physiologically active protein is an antibody.

(11) The method according to the above (10), wherein the antibody is an IgG antibody.

(12) The method according to the above (10) or (11), wherein the antibody is a humanized monoclonal antibody.

(13) The method according to (12), wherein the antibody is a humanized anti IL-6 receptor antibody.

(14) The method according to (12), wherein the antibody is a humanized anti-HM1.24 antigen monoclonal antibody.

(15) The method according to (12), wherein the antibody is a humanized antiparathyroid hormone related peptide antibody (anti PTHrP antibody).

(16) The method according to any one of (1) to (9), wherein the physiologically active protein is granulocyte colony stimulating factor.

(17) The method according to any one of (1) to (16), wherein the particles are removed by filter filtration.

(18) The process according to (1), wherein the sample containing the physiologically active protein is brought into a low-conductive acidic or alkaline aqueous solution, and the buffer is added to the resulting sample to adjust the pH to a pH below the isoelectric point of the physiologically active protein. 1) how to do it.

(19) The physiologically active protein according to (1), wherein the antibody-containing sample is subjected to affinity chromatography of Protein A or Protein G, eluted with a low conductivity acidic aqueous solution, and buffered in the resulting eluate. Step 1) is carried out by adding to adjust the pH to a pH below the isoelectric point of the antibody.

(20) The method according to (18) or (19), wherein the buffer solution is an aqueous Tris solution.

(21) The purified bioactive protein obtained by the method in any one of said (1)-(20).

(22) The manufacturing method of the medical protein preparation containing the refinement | purification process using the method in any one of said (1)-(20).

Best Mode for Carrying Out the Invention

The bioactive proteins contained in the sample containing the bioactive protein purified by the method of the present invention are, for example, granulocyte colony stimulating factor (G-CSF), granulocyte macrophage colony stimulating factor (GM-CSF), erythropoietin (EPO). ), Hematopoietic factors such as thrombopoietin, cytokines such as interferon, IL-1 and IL-6, monoclonal antibodies, tissue plasminogen activating factor (TPA), urokinase, serum albumin, blood coagulation factor VIII factor, Leptin, insulin, stem cell growth factor (SCF) and the like, but are not limited to these. Among the proteins, antibodies such as G-CSF and monoclonal antibodies are preferred, and more preferably monoclonal antibodies. Monoclonal antibodies are preferred in embodiments of the invention which are performed using Protein A / G affinity chromatography. Antibodies are classified as IgG, IgA, IgE, IgD and IgM, although IgG antibodies are preferred.

A "physiologically active protein" is one having a biological activity substantially the same as that of a physiologically active protein of a mammal, in particular a human being, including a natural one or one obtained by genetic recombination, but preferably one obtained by genetic recombination. The bioactive protein by a genetic recombination method is bacterial cells such as E. coli; Yeast cells; It can be prepared in cultured cells derived from animals such as Chinese hamster ovary (CHO) cells, C 127 cells, COS cells, etc., which are isolated and purified by various methods before use. Proteins obtained by genetic recombination include those having the same amino acid sequence as a natural protein and those that retain the biological activity as deletions, substitutions, and additions of one or more amino acids in the amino acid sequence. In addition, physiologically active proteins include those chemically modified by PEG and the like.

When the physiologically active protein is a glycoprotein, there is no particular limitation as to the origin of the sugar chain, but a sugar chain added to the mammalian cell is preferable. Mammalian cells include, for example, Chinese hamster ovary cells (CHO cells), BHK cells, COS cells, and cells derived from humans, among which CHO cells are most preferred.

When the physiologically active protein is EPO, EPO may be produced by any method, for example, obtained from human urine by various methods, or by genetic engineering techniques (for example, Japanese Patent Application Laid-Open No. 61-12288). It is produced by bacteria such as Escherichia coli, yeast, Chinese hamster ovary cells (CHO), BHK cells, COS cells, human-derived cells and the like, and extracted and purified by various methods before use. Also included are EPO chemically modified by PEG and the like (see International Patent Application Publication No. WO90 / 12874). It also includes chemically modified EPO without sugar chains by PEG or the like. Also included in the N-linked glycosylation site or O-linked glycosylation site in the amino acid sequence of EPO is an EPO analog that is modified to increase one or more glycosylation sites (for example, see Japanese Patent Application Laid-Open No. 8). -151398, Japanese Patent Application Laid-open No. Hei 8-506023). In addition, the number of glycosylation sites may be increased, but the amount of sugar chains may be increased by increasing the content of sialic acid or the like.

When the physiologically active protein is G-CSF, G-CSF can be used as long as it is purified G-CSF with high purity. The G-CSF in the present invention may be produced by any method, for example, cultured cell lines of human tumor cells, extracted and purified from various methods therefrom, or by E. coli by genetic engineering techniques. Bacteria of; Yeast; Animal hamster ovary (CHO) cells, C127 cells, animal-derived culture cells such as COS cells and the like, extracted and separated and purified by various methods are used. Preferably produced by genetic recombination in E. coli, yeast or CHO cells. Most preferably produced by genetic reprocessing in CHO cells. Also included are G-CSFs chemically modified by PEG and the like (see International Patent Application Publication No. WO90 / 12874).

When the bioactive protein is a monoclonal antibody, the monoclonal antibody may be produced by any method. The monoclonal antibody basically immunizes the sensitizing antigen according to a conventional immunization method using a known technique, fuses the obtained immune cells with known parental cells by a conventional cell fusion method, and then performs a conventional screening method. It can produce by screening antibody producing cells which are monoclonal.

Alternatively, the antibody gene is cloned from the hybridoma and inserted into a suitable vector, which is introduced into the host using genetic recombination techniques, and the resulting recombinant antibody can also be used in the present invention (e.g., Carl, AK Borrebaeck, James, W. Larrick, THERAPEUTIC MONOCLONAL ANTIBODIES, Published in the United Kingdom by MACMILLAN PUBLISHERS LTD, 1990). Specifically, cDNA of the variable region (V region) of an antibody is synthesize | combined from the mRNA of a hybridoma using reverse transcriptase. When DNA encoding the V region of the desired antibody is obtained, the DNA is linked to the DNA encoding the desired antibody constant region (C region), and the DNA is inserted into the expression vector. Alternatively, the DNA encoding the V region of the antibody may be inserted into an expression vector containing the DNA of the antibody C region. The DNA construct is inserted into the expression vector so that it is expressed under the control of an expression control region, eg, an enhancer or a promoter. Next, the host cell can be transformed with this expression vector to express the antibody.

In the present invention, a genetically modified genetically modified antibody such as a chimeric antibody, a humanized antibody, or the like may be used for the purpose of lowering heterologous antigenicity to humans. These modified antibodies can be produced using a known method. A chimeric antibody is an antibody consisting of a variable region of a heavy chain and a light chain of a mammal other than human, for example, a mouse antibody, and a constant region of a heavy chain and a light chain of a human antibody, and the DNA encoding the variable region of a mouse antibody is invariant of a human antibody. It can be obtained by linking with a DNA encoding a region, inserting it into an expression vector, and introducing into a host to generate an antibody.

Humanized antibodies are also referred to as reshaped human antibodies and are obtained by implanting complementarity determining regions (CDRs) of mammals, such as mouse antibodies, other than humans into the complementarity determining regions of human antibodies. Its standard genetic recombination procedures are also known. Specifically, a DNA sequence designed to connect the CDRs of a mouse antibody and a framework region (FR) of a human antibody is synthesized from several oligonucleotides prepared to have a portion overlapping with a terminal portion by the PCR method. The DNA thus obtained is linked with DNA encoding the antibody constant region of human, and then inserted into an expression vector, which is introduced into a host to generate an antibody (European Patent Application Publication No. EP 239400 and International Patent Application Publication No. WO 96 /). 02576). The FRs of human antibodies linked via CDRs are chosen such that the complementarity determining regions form good antigen binding sites. If desired, the complementarity determining regions of the reconstituted humanized antibody can be substituted for amino acids in the framework regions of the variable regions of the antibody (Sato, K. et al., Cancer Res. (1993) 53 , 851-856).

As such a reconstituted humanized antibody, a humanized anti IL-6 receptor antibody (hPM-1) can be given as a preferred example (see International Patent Application Publication No. WO92-19759). Humanized anti-HM1.24 antigen monoclonal antibodies (see International Patent Application Publication No. WO98-14580), humanized anti-thyroid hormone related peptide antibodies (anti PTHrP antibodies) (see International Patent Application Publication No. WO98-13388), humanized anti Tissue factor antibodies (see International Patent Application Publication No. WO99-51743) and the like are also preferred antibodies for use in the present invention.

Moreover, the acquisition method of a human antibody is also known. For example, human lymphocytes are sensitized in vitro with cells expressing a desired antigen or a desired antigen, and sensitized lymphocytes are fused with human myeloma cells, eg, U266, to obtain a desired human antibody with binding activity to the antigen. (See Japanese Patent Application Laid-open No. Hei 1-59878). In addition, a desired human antibody can be obtained by immunizing a transgenic animal having all repertoires of the human antibody gene with an antigen (International Patent Application Publication Nos. WO 93/12227, WO92 / 03918, WO94 / 02602, WO94 / 25585, WO96). / 34096 and WO96 / 33735). In addition, techniques for obtaining human antibodies by panning using human antibody libraries are also known. For example, the variable region of a human antibody can be expressed as a single-chain antibody (scFv) on the surface of the phage by phage display, and phage binding to the antigen can be selected. Interpreting the gene of the selected phage can determine the DNA sequence encoding the variable region of the human antibody that binds the antigen. Once the DNA sequence of the scFv that binds to the antigen is known, a suitable expression vector can be prepared based on the sequence to obtain a human antibody. Such methods are already well known and can be referred to WO92 / 01047, WO92 / 20791, WO93 / 06213, WO93 / 11236, WO93 / 19172, WO95 / 01438 and WO95 / 15388.

Also preferred are human antibodies produced from transgenic animals and the like.

The antibodies used herein also include antibody fragments such as Fab, (Fab ') ₂ , Fc, Fc' and Fd and reconstituted antibodies such as monovalent or bivalent single chain antibodies (scFv).

In the present invention, "physiologically active protein-containing sample" or "antibody-containing sample" means culture medium of mammalian cells, such as CHO cells, preferably containing physiologically active protein molecules or antibody molecules obtained by culture. The thing which performed constant processing, such as partial purification.

In a preferred embodiment of the present invention, impurities in the bioactive protein-containing sample are removed by a method comprising the following steps:

1) making a sample containing a bioactive protein into a low conductivity aqueous solution at a pH below the isoelectric point of the bioactive protein; And

2) removing the generated particles.

The impurity removed by the method of the present invention may be any substance as long as it is a substance other than the desired protein. Examples of impurities include DNA contaminants, viruses, Protein A (eluted from columns), endotoxins, HCP (host cell-derived proteins), and medium components Hy-Fish (FL) and IGF, but preferably DNA contaminants. Or a virus. As used herein, "DNA contaminant" refers to DNA in a sample containing a physiologically active protein, and includes DNA from a host and DNA from a contaminated virus.

There is no restriction | limiting in particular in the virus removed by the method of this invention, Any virus may be removed and DNA virus and RNA virus are included. RNA viruses include retroviruses such as X-MuLV, Leo viruses such as Reo3, and parvoviruses such as MVM. Specific examples of viruses removed by the method of the present invention include, for example, X-MuLV, PRV, Reo3, MVM, VSV, herpes simplex, CHV, Sindbis, mumps, vaccinia, Measle, Rubella, influenza, herpes zoster , Cytomegalo, parainfluenza, EB, HIV, HA, HB, NANB, ATL, ECHO and parvovirus and the like, but are preferably X-MuLV, Reo3, MVM and PRV.

In the present invention, " low conductivity solution " is usually an aqueous solution having a molar concentration of 0 to 100 mM, preferably 0 to 50 mM, more preferably 0 to 30 mM, or an ionic strength of 0 to 0.2, preferably An aqueous solution of 0 to 0.12 or an aqueous solution of 0 to 300 mS / m, preferably 0 to 200 mS / m, more preferably 0 to 150 mS / m.

The isoelectric point of the bioactive protein is a value of pH at which the charge of the bioactive protein in appearance is lost. The isoelectric point can be measured by a method known to those skilled in the art, and can be measured, for example, by an isoelectric focusing method for obtaining a pH at which a bioactive protein does not move by electrophoresis in solutions of various pH levels. The pH below the isoelectric point of the bioactive protein is preferably the pH below the isoelectric point of the bioactive protein.

In the method of the present invention, when the impurity is DNA, it is preferable to positively charge the physiologically active protein and negatively charge the DNA by lowering the pH below the isoelectric point of the physiologically active protein.

Usually, since DNA has a very strong negative ion charge by the phosphate group in the backbone (the pK value of the phosphate group in the strong acid phosphate diester bond of the nucleic acid is about 1), the pH for negatively charging the DNA is particularly limited. Instead, a preferable pH below the isoelectric point of the physiologically active protein can be used. Since the required pH level will vary for different types of physiologically active proteins, one skilled in the art will prepare a plurality of samples having different pH as known methods (e.g. By measuring a parameter such as a recovery rate), it is possible to select a preferred pH below the isoelectric point of the bioactive protein. Such pH is usually pH 2.0 or more, preferably pH 3.0 or more, particularly preferably pH 4.0 or more.

In order to confirm that the DNA is negatively charged, a known method, for example, using a titration curve (ETC) by electrophoresis (see Ion Exchange Chromatography Principles and Methods, Pharmacia (now Amersham Biosciences), p52 to p56) You can investigate by.

In the method of the present invention, the biologically active protein-containing sample may be brought into a low-conductive acidic or alkaline aqueous solution, and a buffer may be added to the sample obtained to adjust the pH to a pH below the isoelectric point of the bioactive protein.

Thus, in another preferred embodiment of the present invention, impurities in the bioactive protein-containing sample are removed by a method comprising the following steps:

1) making the biologically active protein-containing sample into a low conductivity acidic or alkaline aqueous solution;

2) adding a buffer to the resulting sample to adjust the pH to a pH below the isoelectric point of the bioactive protein; And

3) removing the generated particles.

Impurities removed by the method of the present invention are as described above.

In the present invention, " low conductivity acidic aqueous solution " means an aqueous solution having an molar concentration of 0 to 100 mM, preferably 0 to 50 mM, more preferably 0 to 30 mM, or an ionic strength of 0 to 0.2, preferably Aqueous solution of 0 to 0.12 or an aqueous solution having conductivity of 0 to 300 mS / m, preferably 0 to 200 mS / m, more preferably 0 to 150 mS / m, pH 2.0 to 3.9, preferably pH 2.0 to An aqueous solution of 3.0 is mentioned. The acidic aqueous solution can be selected from aqueous solutions such as hydrochloric acid, citric acid and acetic acid. Depending on the type of physiologically active protein or antibody to be purified, the type, conductivity and pH of the low-conductive acidic aqueous solution to be used are different, and those skilled in the art can perform the preliminary tests according to the methods described herein to determine their optimum conditions. It can be set easily.

In addition, the "low conductivity alkaline aqueous solution" used in the method of the present invention means an aqueous solution having a molar concentration of 0 to 100 mM, preferably 0 to 50 mM, more preferably 0 to 30 mM or an ionic strength of 0 to 0.2, preferably an aqueous solution having 0 to 0.12 or an aqueous solution having a conductivity of 0 to 300 mS / m, preferably 0 to 200 mS / m, more preferably 0 to 150 mS / m, and generally pH 7.5 to 13 means aqueous solution (pH varies depending on the type of bioactive protein or antibody to be purified).

In the method of the present invention, the sample containing the physiologically active protein is brought into an acidic or alkaline aqueous solution of low conductivity, and then the buffer is added to the sample obtained to adjust the pH to a pH below the isoelectric point of the physiologically active protein. Examples of the buffer include Tris-HCl, phosphate, Tris, Na ₂ HPO ₄ and NaOH.

In the present invention, for example, when the physiologically active protein is an antibody, in general, the antibody-containing sample is subjected to affinity chromatography of Protein A or Protein G, eluted with a low conductivity acidic aqueous solution, and a buffer solution in the resulting eluate. Can be added to adjust the desired pH to a range below the isoelectric point of the bioactive protein.

Thus, in another preferred embodiment of the present invention, impurities in the bioactive protein containing sample are removed by a method comprising the following steps:

1) eluting the sample containing the antibody to affinity chromatography of Protein A or Protein G in an acidic solution of low conductivity;

2) adding a buffer to the resulting eluate to adjust the pH to a pH below the isoelectric point of the bioactive protein; And

3) removing the generated particles.

Impurities removed by the method of the present invention are as described above.

An acidic aqueous solution of low conductivity for use in this method may be selected from the above, and buffer solution can be cited as an example, the Tris-HCl, phosphate, Tris, Na ₂ HPO ₄ and NaOH example.

In the method of the present invention, the solution adjusted to the pH below the isoelectric point of the bioactive protein in this step in turn generates particles (ie, cloudy). By removing these particles by filter filtration, impurities such as DNA contaminants can be efficiently removed. As a filter used for filtration, 1.0-0.2 micrometer Cellulose Acetate Filter System (made by Corning), TFF, etc. can be used, for example, It is not limited to these.

Moreover, the method for removing the said particle | grain also has a centrifugal operation etc., What is necessary is just an arbitrary method which can remove a particle efficiently, It is not limited to filter filtration.

The inventors do not wish to be bound by a particular theory, but if the impurity is DNA, the particle is assumed to be a complex formed between the bioactive protein and the DNA. If the pH is lower than the isoelectric point of the protein, the protein is positively charged, and the DNA is negatively charged, whereby a complex of DNA and protein is formed. In addition, it is thought that the composite becomes more easily formed by switching to the low conductivity aqueous solution. Filter removal of the particles results in the loss of a small amount of the bioactive protein contained in the DNA-physiologically active protein complex, but only a few percent of the total bioactive protein, and as described in the Examples below, About 90% can be recovered.

In addition, since this DNA-physiologically active protein complex is generated on the column resin, it is assumed that Protein A / G column chromatography alone does not effectively separate DNA contaminants and physiologically active proteins. The bioactive proteins purified by the method of the present invention can also be purified and used in pharmaceutical preparations by cation exchange chromatography, anion exchange chromatography, hydroxy apatite chromatography, or a combination thereof.

As a DNA quantification method, it measures by Threshold Total DNA quantification method, and DNA extraction operation is performed prior to a measurement, but it is not limited to these.

As a virus quantification method, RTID / Q-PCR and Q which can quantify TCID ₅₀ (tissue culture infective dose (50%); 50% culture cell infectious dose), and the amount of virus in fractions, as indicators of viral infectivity to detection cells Although measured by -PCR, it is not limited to these.

Although the present invention will be described in more detail by the following embodiments, the scope of the present invention is not limited thereto. Various changes and modifications are possible to those skilled in the art based on the description of the present invention, and such changes, modifications and the like are also included in the present invention.

Example 1: Examination of the buffer composition of Protein A affinity chromatography in hPM-1 (humanized anti IL-6 receptor antibody) purification

1.1. Test Methods

(1) test material (antibody-containing sample)

hPM-1 Antibody (Humanized Anti IL-6 Receptor Antibody) Production CHO Cell Culture Supernatant (hereinafter referred to as CM) (Cells Centrifuged: -80 ° C Preserved) Sample containing 0.22 μm Cellulose Acetate (called CA) Filter System ( CORNING) was used to filter and used for purification review. In addition, the hPM-1 antibody was used in the method described in Reference Example 2 of Japanese Patent Application Laid-Open No. 8-99902 using the human elongation factor Iα promoter described in Example 10 of International Patent Application Publication No. WO92 / 19759. It prepared according to (Isoelectric point: pH 9.0).

(2) device

When examining hydrochloric acid

HPLC: L-6200 Intelligent Pump (HITACHI)

      L-4200 UV-VIS Detector (HITACHI)

      D-2500 Chromato-Integrator (HITACHI)

Column: HR5 / 2 from Pharmacia, 5 mm I.D. × 20 mm H

Media: POROS 50A (PerSeptive), 0.4 ml

       Lot; A250-039, Code; SPECIAL

At particle review

HPLC: Waters PrepLC4000 System (Waters)

      Waters2000 System Controller (Waters)

      Waters486 Tunable Absorbance Detector (Waters)

      Waters741 Data Module (Waters)

Spectrophotometer: U-2000 (HITACHI)

Column: XK26 (Pharmacia), 26 mm I.D. × 100 mm H

Media: POROS 50A (PerSeptive), 53 ml

       Lot; A250-039, Code; SPECIAL

(3) analysis and quantification

hPM-1 Assay:

It is quantified by reverse phase HPLC using a PLRP-S column (Polymer Laboratories) by a linear concentration gradient method.

DNA amount measurement method:

Measured by Threshold Total DNA Assay. DNA extraction procedure (Wako Pure Chemicals Industries, Ltd. using DNA extractor kit) is performed prior to measurement. In addition, Threshold Total DNA Quantitation Kit (made by Molecular Devices) is used for the measurement.

Turbidity Measurement:

In order to monitor the situation of particle formation, absorption at 660 nm by the spectrophotometer U-2000 (HITACHI) is measured on the measurement sample.

1.2. Review of elution conditions

The elution conditions in various compositions of the buffer used as the eluate in Protein A affinity-chromatography were examined by measuring the hPM-1 recovery rate and the DNA removal status by the eluate. The antibody-containing sample was provided in a column under the conditions shown in Table 1 below. Protein A resin was equilibrated with the equilibrium buffer shown in Table 1, and the said antibody containing sample was then filled, and wash 1, wash 2, and elution were performed after that. Elution profile was monitored at A 280 nm and the peak of the protein was isolated. In the table below, C-P Buffer represents citric acid-phosphate buffer.

Dissolution Act 1 Elution Act 2 Elution Act 3 Equilibration 1M NaCl / 100mM C-P Buffer pH7.5 1M NaCl / 10mM C-P Buffer pH7.5 1M NaCl / 100mM C-P Buffer pH7.5 Cleaning 1 1M NaCl / 100mM C-P Buffer pH7.5 1M NaCl / 10mM C-P Buffer pH7.5 1M NaCl / 100mM C-P Buffer pH7.5 Cleaning 2 100 mM C-P Buffer pH7.5 10 mM C-P Buffer pH7.5 100 mM C-P Buffer pH7.5 Elution 100 mM C-P Buffer pH2.6 2.5 mM HCl pH2.6 2.5 mM HCl pH2.6

In elution methods 1, 2 and 3, no difference in chromatography was found.

Each eluted fraction was adjusted to pH 7.0 with 300 mM Tris solution, and particles were formed in the hydrochloric acid eluted fraction (elution method 2, elution method 3). In addition, a study was conducted to find a correlation between particle formation, recovery rate of hPM-1, and residual DNA amount.

In order to investigate particle correlation, NaCl was added to the hydrochloric acid eluate in elution method 2, and the correlation between the added NaCl concentration (0 mM, 50 mM, 100 mM) and various factors was analyzed. In the analysis of the correlation between the added NaCl concentration and various factors, each Protein A elution fraction with NaCl was adjusted to pH 7.0 with 300 mM Tris solution, which was then filtered or not filtered by 0.22 μm CA Filter or not. Samples were prepared. The hPM-1% recovery (filtered samples only) and the amount of remaining DNA for the sample were measured.

1.3. % Recovery

The% recovery rate of hPM-1 in each elution condition was measured. As a result, the% recovery rate in the elution method 1 was good at 98.6%. On the other hand, the variation was 83.8% to 98.1% in the% recovery rate in the elution method 2, and 83.5% to 97.3% in the recovery rate in the elution method 2. Was supposed to. In the examination (elution method 2) which enlarged the purification scale, it confirmed that the% collection | recovery rate of hPM-1 showed 90% or more stably. Therefore, even in the case of hydrochloric acid elution, it was found that the% recovery rate of hPM-1 was good.

1.4. Relationship between Added NaCl Concentration in Hydrochloric Acid Eluate and Various Factors

Table 2 shows the results of examining the correlation between the added NaCl concentration in the hydrochloric acid eluate and various factors.

NaCl concentration 0 mM 50 mM 100 mM Turbidity (before pH adjustment) 0.004 0.007 0.011 Turbidity (after pH adjustment) 0.252 0.049 0.020 hPM-1% Recovery (after filtration) (%) 81 86 88 DNA volume (before filtration) (pg DNA / mg hPM-1) 98 220 241 DNA volume (after filtration) (pg DNA / mg hPM-1) 11 30 250

The hPM-1% recovery after filtration was 88% in 100 mM NaCl-added samples, 86% in 50 mM NaCl, and 81% in 0 mM NaCl. Regarding the amount of remaining DNA, the samples added with 0 mM NaCl showed low values in the samples before and after filtration, and in particular, the samples with 0 mM NaCl added after filtration had a very low value of 11 pg DNA / mg hPM-1.

In addition, the higher the turbidity value in the sample after pH adjustment, the lower the hPM-1% recovery and the remaining DNA amount after filtration. This result indicates that hPM-1 and DNA are most likely involved in particle formation. Perhaps by adjusting the pH to 7.0, hPM-1 and DNA interact to generate particles. In order to increase the hPM-1% recovery, it is preferable to increase the NaCl concentration of the HCl eluate, and conversely, to reduce the amount of remaining DNA, it is preferable not to add NaCl.

Example 2: Purification of Humanized Anti-PTHrP Antibodies

Humanized anti-PTHrP antibody-containing samples (cultured supernatants cultured with CHO cells were filtered with 0.45 and 0.2 μm CA SARTOBRAN P filters (sartorius)) were purified using Protein A affinity column chromatography under the following conditions. Anti-PTHrP antibodies were prepared by the method described in International Patent Application Publication No. WO98 / 13388 (isoelectric point: pH 8.3).

2.1. Experimental conditions

Purification Device: AKTA explorer (Amersham Pharmacia Biotech)

Column: HR5 / 5, C10, XK-26 (Amersham Pharmacia Biotech)

Resin: rProtein A Sepharose Fast Flow

Load: culture supernatant direct load (pH 6.6∼7.5)

Elution fraction adjustment: The elution fraction is adjusted to various pHs by 1M Tris aqueous solution, and it removes DNA by filtering by 0.2 micrometer Cellulose Acetate (henceforth CA) (refer conditions in (1) below).

The Protein A column was equilibrated with 150 mM NaCl-added citric acid-phosphate buffer (pH 7.5) before loading the antibody containing CM. Subsequently, wash with 150 mM NaCl-added citric acid-phosphate buffer (pH 7.5) to remove unbound impurities, further wash with citric acid-phosphate buffer (pH 7.5) to lower conductivity, and then with 20 mM aqueous citric acid solution. Elution was performed. Elution profile was monitored at A 280 nm and protein peaks were isolated. The following conditions were examined using this Protein A elution fraction.

2.2. Review of Residual DNA Removal Conditions in the Eluate

In order to remove residual DNA efficiently, the optimum pH conditions at the time of filter filtration were examined. The Protein A elution fraction was adjusted to the following pH (fine (2.7), 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0 and 7.5) with 1.0 M Tris aqueous solution. Thereafter, each sample was left for a certain time and filtered through a 0.22 μm CA filter. Then, DNA was quantified by adjusting to pH 7 with 1.0 M Tris aqueous solution. The examined pH, standing time, and remaining DNA amount are shown in Table 3 below.

Removal of Residual DNA (Unit: pg / mL) pH 7.5 pH 7.0 pH 6.5 pH 6.0 pH 5.5 pH 5.0 pH 4.5 pH 4.0 Direct
(pH 2.7) 0hr. 984 83.3 53.8 <22.5 <15.0 17.2 54.1 32,052 40,878 6hr. 816 51.9 <15.0 <22.5 <15.0 <15.0 44.0 38,172 42,078 24hr. 310 46.6 <15.0 <22.5 <15.0 <15.0 39.7 42,528 30,222

(DNA in culture supernatant: 6,637,200 pg / mL, DNA in unfiltered sample: 25,110 pg / mL)

As can be seen from the table, in all cases where the samples were left for 0, 6 and 24 hours, the residual DNA amount was below the detection limit at pH 5.5 and 6.0. Also, regarding the DNA removal situation, it was observed that the DNA removal efficiency was deteriorated as the pH was increased or decreased around the pH 5.5 and 6.0.

Example 3: Purification of Humanized Anti-HM1.24 Antigen Monoclonal Antibodies

Samples containing humanized anti-HM1.24 antigen monoclonal antibody (culture supernatants incubated with CHO cells) were purified using Protein A affinity column chromatography under the conditions described in Table 4 below. In addition, anti-HM1.24 antigen monoclonal antibodies were prepared by the method described in International Patent Application Publication No. WO98 / 14580 (isoelectric point: pH 9.0).

3.1. Experimental conditions

Column: rProtein A FF, 5 mL (16 mm ID x 25 mm H)

Flow rate: 5 mL / min (150 cm / h)

Sample: Directly load the culture supernatant

Equilibrium (20 CV) 10 mM C-P Buffer, 1M Nacl, pH 7.5 Load CM direct load Cleaning 1 (20 CV) 10 mM C-P Buffer, 1M Nacl, pH 7.5 Clean 2 (20 CV) 10 mM C-P Buffer, pH 7.5 Elution (10 CV) Citric Acid, pH 2.5 Clean 3 (4 CV) 0.1M NaOH

The Protein A column was fully equilibrated with 150 mM NaCl-containing citric acid-phosphate buffer pH 7.5 and then loaded with the antibody-containing CM. Subsequently, it was washed with 150 mM NaCl-containing citric acid-phosphate buffer pH 7.5 to remove unbound impurities, and further washed with citric acid-phosphate buffer pH 7.5 to lower conductivity, followed by elution with 20 mM aqueous citric acid solution. . Elution profile was monitored at A280 nm and protein peaks were isolated. The Protein A elution fraction was used to examine the conditions below.

3.2. Review of Residual DNA Removal Conditions in the Eluate

In order to remove residual DNA efficiently, the optimum pH at the time of filter filtration was investigated. The Protein A elution fraction was adjusted to the following pH level (pH = 4.5-7.5) with 1.0 M Tris aqueous solution. Then, each sample was left to stand for a certain time and filtered with a 0.22 µm CA filter. It was then adjusted to pH 7 with 1.0 M Tris aqueous solution and quantified by humanized anti-HM1.24 antigen monoclonal antibody by DNA quantification and reversed phase HPLC. Table 5 below shows the measurement results of the amount of DNA, and Table 6 below shows the results of the yield measurement of the humanized anti-HM1.24 antigen monoclonal antibody.

Removal of Residual DNA (Unit: pg / ml)

Experiment 1 pH 7.5 pH 6.5 pH 5.5 0 h 1142 624 113 6 h 3288 1157 117

(DNA in culture supernatant: 235 200 pg / ml)

Experiment 2 pH 5.5 pH 5.0 pH 4.5 0 h 137 67 86 6 h 94 34 164

(DNA in culture supernatant: 5448000 pg / ml, DNA in sample before filter filtration treatment: 4330 pg / ml)

% Recovery of humanized anti-HM1.24 antigen monoclonal antibody by filtration pH 5.5 pH 5.0 pH 4.5 0 h 98.1% 89.6% 87.8% 6 h 89.3% 91.1% 98.6%

Although a large amount of DNA was still present in the sample after Protein A affinity chromatography purification, in the experiment 1, the amount of DNA decreased as the pH was decreased to 7.5, 6.5, and 5.5, and the time was zero hours later than the six hours. This DNA removal rate tended to be high. In Experiment 2, the same experiment was conducted under the conditions of pH = 4.5, 5.0, and 5.5, but DNA was removed to the same extent, regardless of pH and standing time, within the test range. Calculation of the% recovery also found that humanized anti-HM1.24 antigen monoclonal antibody was hardly lost.

Example 4: Purification of Granulocyte Colony Stimulating Factor (G-CSF)

The following conditions were examined using the G-CSF containing sample (Culture to CHO cells: Chugai Pharmaceutical Co., Ltd) (isoelectric point: pH 5.5-5.7).

4.1. Review of Residual DNA Removal Conditions in the Eluate

In order to remove residual DNA efficiently, the optimum pH at the time of filter filtration was investigated. The G-CSF-containing sample was diluted with a low conductivity acidic solution (2.5 mM HCl aqueous solution), a low conductivity acidic aqueous solution was further made using 20% hydrochloric acid, and then a DNA sample was added. The G-CSF-containing sample thus treated was adjusted to the following pH level (pH = 4.3 or 6.6) with 1.0 M Tris aqueous solution, followed by filtration with a 0.22 μm CA filter. Thereafter, DNA of fractions before and after filtration was quantified. Table 8 below shows the results of measuring the amount of DNA.

Removal of Residual DNA (Unit: pg / ml) PH at filtration pH 6.6 pH 4.3 Before filtration 4.3 × 10 ⁵ 4.3 × 10 ⁵ After filtration 2.8 × 10 ⁴ <90

From the above results, it was confirmed that when the sample was filtered to pH 4.3, the DNA amount was efficiently reduced from the G-CSF-containing sample containing a large amount of DNA so that the residual DNA amount was below the detection limit.

Example 5: Virus Removal Effect in hPM-1 (Humanized Anti IL-6 Receptor Antibody) Purification

5.1 Test Material (Antibody-Containing Sample)

X-MuLV, Reo3 and MVM were added to samples containing CHO cell culture supernatant (CM) (cells were removed by centrifugation: -80 ° C. preservation) producing hPM-1 antibody (humanized IL-6 receptor antibody). After addition, each CM was filtered using a 0.45 micrometer filter (Bottle Top Filter: CORNING Co., Ltd.), and was used for purification examination. In addition, hPM-1 antibody was produced similarly to Example 1. In addition, each virus used was obtained from the American Type Culture Collection (ATCC).

5.2 Purification by rProtein Column Chromatography

The virus-added sample prepared in 5.1 was purified by rProtein Column Chromatography. Specific conditions are as follows.

Resin: rProtein A Sepharose Fast Flow

Instrument: AKTA explorer 100, AKTA purifier

Columns: XK16 / 20, XK16 / 40

Resin height: 11.5 cm

Elution conditions

Equilibration: 1 mol / L NaCl, 20 mmol / L C-P Buffer, pH 7.5 ± 0.2, Conductivity 8.5 ± 0.5 S / m

Cleaning 1: 1 mol / L NaCl, 20 mmol / L C-P Buffer, pH 7.5 ± 0.2, conductivity 8.5 ± 0.5 S / m

Clean 2: 10 mmol / L C-P Buffer, pH 7.7 ± 0.2, conductivity 165 ± 20 mS / m

Elution: 2.5 mmol / L HCl, pH 7.7 ± 0.2, conductivity 107 ± 10 mS / m

5.3 Low pH Treatment

The elution fraction obtained in 5.2 was adjusted to pH 3.2 ± 0.1 with 1 mol / L hydrochloric acid, and kept at room temperature 15 ± 5 ° C for at least 30 minutes. Each eluted fraction was then adjusted to pH 7.2 ± 0.1 with 300 mmol / L Tris solution. Among them, 40.0 mL of the glass fiber filter (manufactured by Millipore) (0.2 μm, manufactured by PALL) was used as the primary side, and BioInert (0.2 μm, manufactured by PALL). Pressure filtration was carried out to 0.03 ± 0.01 MPa using a filtration unit connected to the secondary side.

5.4 Detection of Viruses

All samples taken were measured with TCID ₅₀ . In addition, in the clearance capacity test of X-MuLV and MVM, RT / Q-PCR and Q-PCR, which can quantify the amount of virus in the fraction, in addition to TCID ₅₀ , which is an indicator of viral infectivity on detection cells, Measurement by

5.5 Results

The measurement result of 5.4 is shown in the following table | surfaces.

Virus titer (TCID ₅₀ method: Log ₁₀ / mL)
Reo3 MVM Run 1 Run 2 Run 1 Run 2 Before filtration 5.76 5.76 4.80 4.18 After filtration ≤1.03 ≤1.03 ≤1.03 ≤1.03

Virus Titer (PCR: Log ₁₀ Copies / 5 μL)
X-MuLV MVM Run 1 Run 2 Run 1 Run 2 Before filtration 5.05 4.77 4.18 2.83 After filtration ≤1.90 ≤1.90 ≤1.30 ≤1.90

As described above, it was confirmed that the purification process of the present invention yielded a very high Logarithmic Reduction Value (LRV) for all viruses, and was removed to below the limit of quantification after low pH treatment and filtration.

By the method of the present invention, impurities such as DNA contaminants and viruses can be efficiently removed in a very simple manner, and purification of physiologically active proteins, especially antibodies, is much more effective. If the impurity is DNA, the DNA concentration is at a very low concentration (e.g. 22.5 pg / ml) .If the impurity is a virus, the virulence value is at a very low value (e.g. 1.03 (Log ₁₀ / mL by TCID ₅₀ method). By the notation of)). In addition, the cost of the present invention can be reduced, and the technical significance is particularly significant.

Claims (22)

A method for removing impurities in a bioactive protein-containing sample, comprising the following steps: 1) making a sample containing a physiologically active protein into an aqueous solution of pH and low conductivity below the isoelectric point of the physiologically active protein, wherein the molar concentration of the low conductivity aqueous solution is greater than 0 mM and 100 mM or less; And 2) removing the generated particles. delete The method of claim 1 wherein the ionic strength of the low conductivity aqueous solution is greater than 0 and less than or equal to 0.2. The method of claim 1 wherein the conductivity of the low conductivity aqueous solution is greater than 0 mS / m and no greater than 300 mS / m. The method of claim 1 wherein the aqueous solution is selected from aqueous solutions of hydrochloric acid, citric acid and acetic acid. The method of claim 1 wherein the pH of the aqueous solution is below the isoelectric point of the bioactive protein and is above pH 2.0. The method of claim 1 wherein the impurity is a DNA contaminant. The method of claim 1 wherein the impurity is a virus. 8. The method according to claim 7, wherein the DNA contaminants in the sample containing the bioactive protein after the DNA contaminant removal treatment have a DNA concentration of 22.5 pg / ml or less. The method of claim 1, wherein the bioactive protein is an antibody. The method of claim 10, wherein the antibody is an IgG antibody. The method of claim 10, wherein the antibody is a humanized monoclonal antibody. The method of claim 12, wherein the antibody is a humanized anti IL-6 receptor antibody. The method of claim 12, wherein the antibody is a humanized anti HM1.24 antigen monoclonal antibody. The method of claim 12, wherein the antibody is a humanized anti parathyroid hormone related peptide antibody (anti PTHrP antibody). The method of claim 1, wherein the bioactive protein is granulocyte colony stimulating factor. The method of claim 1 wherein the particles are removed by filter filtration. The method according to claim 1, wherein the biologically active protein-containing sample is in a low-conductive acidic or alkaline aqueous solution, and the resulting sample is added with a buffer to adjust the pH to a pH below the isoelectric point of the bioactive protein. As a method of performing the process of, Wherein the molarity of the low conductivity acidic or alkaline aqueous solution is greater than 0 mM and no greater than 100 mM. 2. The physiologically active protein according to claim 1, wherein the antibody-containing sample is subjected to affinity chromatography of Protein A or Protein G, eluted with a low conductivity acidic aqueous solution, and the resulting eluate is added with a buffer to pH. As a method for carrying out the process of step 1) by adjusting the pH to below the isoelectric point of the antibody, Wherein the molarity of the low conductivity acidic aqueous solution is greater than 0 mM and no greater than 100 mM. 20. The method of claim 18 or 19, wherein the buffer is an aqueous Tris solution. delete The manufacturing method of the medical protein preparation containing the purification process using the method of Claim 1.